Who set those expectations, based on what criteria, how legitimate are they and what happens if they are not met now, or at some time in the future.
For the most part, it’s a matter of meeting basic expenses. If a bochur wants to learn for X amount of years, and the support promised doesn’t reasonably give him that opportunity, and there are other shidduchim to pursue, he will pursue those.
In my experience, most Torahdik families do not go overboard in their expectations. There are always exceptions, and those stories, true or exaggerated, get the most attention.